Simple Mixtures 2 Flashcards
Mixture of benzene and toluene obeys ____ because ____ and
Raoult’s Law because it behaves ideally and there is no interaction between the two components
Partial pressures of both components are proportional to their respective mole fractions in liquid phase
Partial pressures in a binary components are ___ to their respective ___ in the ____ phase
proportional
mole fractions
liquid
In a binary mixture, the total pressure is the ____ of the ____ of both components
sum
partial pressures
P benzene * ____ P toluene *
>
Pressure-composition phase diagram is used to
describe binary mixtures at a given temperature if vapor pressure and composition of either liquid or vapor phase is known
The variance (F) at liquid only and vapor only region
3: (P,x) or (P,y) T
Variance (F) at liquid + vapor region
2: T, and P or x or y
What will be the phase change if pressure is decreased?
From liquid only to liquid + vapor to vapor only
If a point in l + v region is closer to liquid curve, n vapor ___ n liquid
<
the amount of liquid phase is greater than the amount of vapor phase
Lever rule equation
(ol) (n liquid) = (ov) (n vapor)
Example of binary system that deviates from ideality
acetone-carbon disulfide
How acetone-CS2 system behave
As x CS2 approaches 1, Raoult’s Law is observed.
As x CS2 approaches 0, Henry’s Law is observed.
Behaves like an ideal dilute solution
Henry’s Law vs Raoult’s Law
HL: Pj = Kj xj
RL: Pj = Pj* xj
_____ solutions obey ideal dilute solution laws at the limit of ____ concentration
All; zero
in a temperature-composition (LVE) liquid and vapor curves can be calculated via
Clausius-Clapeyron equation
Describe the appearance of temperature-composition diagram (LVE)
Vapor is above the liquid curve. Both liquid and vapor curve are not straight line (curve). Initial temperature (bp) of toluene is higher than benzene.
Temperature-composition diagram for ideal binary mixture is useful for?
fractional distillation of binary mixtures
In fractional distillation, the binary mixture is ___ until ___ forms.
boiled until vapor forms
In fractional distillation, the vapor formed is richer in the component that has ___ boiling point.
lower
The condensed vapor, ____, is boiled again until it becomes ___ in the component that is more ___.
distillate; pure; volatile
In fractional distillation, the more rounds of boiling-condensation, the ____
purer the distillate
In fractionating columns, vapors rich in ___ volatile component (aka __) rise while vapor rich in ___ volatile component (aka __) collects at the bottom
more volatile; distillate
less volatile; residue
The temperature in the top portion of fractioning column is ___ compared to that bottom portion
lower
Clean separation between two components by fractional distillation is feasible only if?
there is significant difference in their boiling points
Ethanol-water mixtures cannot be separated using fractional distillation because?
It is an azeotrope, do not behave ideally. Whatever vapor is formed, the composition is the same as that of the liquid
The minimum point in the liquid curve that coincides with that of vapor curve implies?
at this temperature, the composition of liquid and vapor phase are identical.
Why azeotrope deviate from ideality?
There is a significant interaction between the molecules of the two components.
A ___ results if two liquids are fully miscible.
single phase
A ___ system is observed when either component has limited solubility in the other.
biphasic system
The region bounded by the curve is the ___ region under the critical temperature
biphasic region
The lever rule is used to ___ in a LLE
determine the relative amount of phases present in the mixture
If xa is closer to zero-mole fraction mark in butanol-water system, the amount of water-rich phase is ___ than the butanol-rich phase
greater
(T/F) Binary mixtures can exhibit lower critical point, higher critical point, and both upper and lower critical point
True
Melting point of solution ___ melting point of pure solvent
less than
Point where the curves of two components will coincide.
eutectic point
What happens at eutectic temperature?
mixture becomes fully solid regardless of its composition
What happens at eutectic composition x E
mixture solidifies entirely without forming two separate liquid and solid phases
Solid melt is not ___ and hence there are ___ phases
homogeneous; two distinct
Equimolar mixture of liquid gallium and arsenic direct forms ___
solid gallium arsenide (GaAs)
What will happen when other compositions of gallium and arsenide is used and not equimolar?
GaAs solidifies first, leaving the liquid mixture
If there are excess arsenide in gallium-arsenide system, what solid will be formed and where?
solid GaAs and solid arsenide will be formed below the melting point of excess arsenide
(T/F) Solid melt for equimolar mixture has two distinct phases
False. Only the compound is present, single phase
(T/F) Binary system can exhibit both formation of eutectic mixture and formation of compound
True
Line passing through the point where hex3cyc will form
peritectic line
What happens at peritectic line?
three phases are in equilibrium:
liquid mixture, solid hex, solid compound hex3cyc
hex3cyc undergoes ___
incongruent melting. it forms a liquid with composition xp and solid hex
(T/F) Acetic acid has limited miscibility with water while ethyl acetate is miscible with both water and ethyl acetate.
False. Ethyl acetate: limited miscibility with water. Acetic acid: miscible for both
Ternary diagram shows the ___
degree of miscibility of three components
The vertices represents ___, line connecting vertices represents ____, and any point inside the triangle represents ____.
vertices: pure solvent
line connecting: mixture of two components
point inside: mixture of three components
The sum of the mole fractions of all three components should be equal to ___
one
The biphasic region in ternary diagram is enclosed with __
binodal curve
Binodal curve is determined by
experimental analysis of phases that separate when varying amount of three components are mixed
The line in binodial curve that connects the composition of aqueous and organic phase
tie line
Point in binodal curve in which two layers that separate will have almost the same composition
plait point
at low concentration, acetic acid is ___ in ethyl acetate than in water
more soluble
